1. Field of the Invention
This invention relates generally to electrical switches and particularly relates to a linear motion switch which is automatically adjusted upon installation.
2. Discussion of Prior Developments
Self adjusting switches have been in use for many years. Switches of this type are frequently used in applications where large tolerances tend to stack up or accumulate between parts thereby requiring an adjustment, setting or calibration of the switch before it may be placed in normal operation. An example of such a switch is shown in U.S. Pat. No. 3,249,727 wherein a switch plunger assembly provides for a frictionally retained telescoping adjustment extending between the frame and door of an automobile. While this type of switch serves its purpose well, it requires the actuation or closing of the car door to effect the setting of the plunger length.
In some applications it is desirable to be able to calibrate or set the length or stroke of a switch actuator without requiring actuation or movement of the components, devices or mechanisms which actuate the switch in normal use. For example, it is often desirable to install hydraulically or pneumatically actuated devices or sub-systems as self-contained preset and pre-adjusted units. If such a hydraulic unit requires a sensor or switch which must be set or calibrated before use, it is most inconvenient, time consuming and potentially messy to fill the system with fluid, mount it for actuation and actuate it just to adjust or set the sensor or switch.
Accordingly, a need exists for a switch which is self adjusting and self calibrating upon its installation and which does not require actuation of the component or device which typically actuates the switch during normal use.